The present invention relates generally to printed materials and more particularly to clamping devices and trimming units for trimming edges of a book.
U.S. Pat. No. 6,030,163 discloses a method for fusing two or more pieces along an edge to produce a volume. The volume can have a skewed spine.
U.S. Pat. No. 5,086,681 discloses transferring books using an infeed conveyor system having a belt. The belt travels at slower speed than conveyor chains to create a slight frictional force on pusher members attached to the conveyor chains. As the books leave the infeed conveyor system, they are impelled into a first trimming station.
A problem associated with prior art trimmers used for trimming books is the delamination of the cover of a book from the interior sheet material. This trim defect is typically called xe2x80x9cchipoutxe2x80x9d.
FIGS. 1 and 2 show a force vector analysis by the present inventors, in which the forces of a straight trim blade at an angle alpha are analyzed as a trimming blade 10 with a straight edge 12 cuts an end of a book 20. Book 20 includes sheet material 26 and a cover 22, connected to sheet material 26 by adhesive 24.
A resultant force FR normal to the blade edge 12 results, with a force component F1 parallel to a tangent line of the cover interaction with the sheet material 26, and a component FN normal to the tangent line. As shown in FIG. 1, as the blade 12 first cuts at the top of the book 26 and cover 22, the normal force FN is directed into the book. At this stage, generally no chipout occurs.
However, as shown in FIG. 2, as the cut progresses through the lower curved section 28 of cover 22, the normal force FN acting on cover 22 is directed away from sheet material 26, and can cause chipout, since the force is directed away from the sheet material 26.
One object of the present invention is to provide a method for producing a skewed spine in a book. Anther alternate or additional object of the present invention is to improve cutting of books, especially of the sides of books adjacent to the spine. Another alternate or additional object of the present invention is to reduce chipout in reciprocating blade trimmers.
European Patent Application No. 1 153 872, which corresponds to commonly-assigned U.S. patent application Ser. No. 09/570,203 filed May 12, 2000, discloses creating a skew in a collated sheet product.
The present invention provides a method for producing a profiled spine in a book having a first side defining a first plane, a second side defining a second plane and a spine, the method comprising the steps of:
clamping the book using a first clamp element contacting the first side and the second clamp element contacting the second side; and
moving the first element with respect to the second element so as to skew the spine by moving at least one of the first side in the first plane and the second side in the second plane.
The present method advantageously permits creation of a skewed spine, which can be advantageous in reducing chip out in trimming devices, for example.
Preferably, the method further includes trimming the skewed spine. The skewed spine may form a skew angle with respect to the first plane, the skew angle preferably being an acute angle. The trimming may proceed from the first side to the second side. The acute skew angle reduces the chipout effect of the trimming.
The present invention also provides a clamp having a first clamping element, a second clamping element for clamping a bound book, and an actuating device moving the first clamping element with respect to the second clamping element to create a shearing force in the book.
The present invention also provides a trimmer having a blade and a clamp according to the present invention.